Manchester United's Sir Alex Ferguson and Real Madrid's Jose Mourinho are two of the most successful managers in the modern game. Combined, the two have won four UEFA Champions League trophies and more than 20 domestic titles. Each has earned the respect of the other over the years, and Ferguson has even been quoted as saying he'd like Mourinho to succeed him at United.

So, then, comparing them would be little more than a case of apples and oranges—right?

Well, since we like to start debates around here, we figured it would be a good idea to fire one up concerning these two. Clearly, Ferguson has had the better, longer, more distinguished career. But how have the two rivals fared against each other?

That's what we're here to tackle today. We'll be examining the 13 matches between the two, with the contests divided up by seasons.

Manchester United took an early lead through Quinton Fortune, but Porto grabbed a victory with two goals from Benni McCarthy, one either side of halftime.

United skipper Roy Keane was sent off in the 87th minute for a stamp on Porto keeper Vitor Baia. It was the 11th red card of his career.

Manchester United 1-1 Porto, Champions League Round of 16, Second Leg, March 9, 2004

Paul Scholes put United ahead on the night, and seemingly into the quarterfinals on away goals, with a first-half header. But Porto's Francisco Costinha scored a last-minute equalizer after United keeper Tim Howard fumbled McCarthy's late free kick.

Porto went on to win the Champions League, and Mourinho—whose joyful celebration after the United win became famous—earned his first two positive results over Ferguson.

2004-05 Season

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Mourinho signed on as Chelsea's manager in the summer and immediately led the cash-infused Blues to their first title in 50 years. Along the way, Chelsea beat United three out of the four times they met.

Chelsea 1-0 Manchester United, Premier League, August 15, 2004

Eidur Gudjohnsen (pictured) scored in the 15th minute, and Mourinho's Chelsea killed off the match in both teams' season opener.

Both the result and the style of play would turn into themes over the course of the season.

2008-09 Season

Mourinho left Chelsea following the 2006-07 season and joined Inter Milan in time for the 2008-09 campaign. Inter and United met, somewhat inevitably, in the Champions League Round of 16, pitting the legendary managers in a rematch of their first encounter back in 2004.

Conclusion

Ferguson and Mourinho haven't met since 2009, but with Mourinho now leading Real Madrid, the two are sure to face off again. Their encounters so far have produced several classics.

Here are the all-time results in matches managed Ferguson against Mourinho:

Played: 13

Mourinho Wins: 6

Ferguson Wins: 2

Draws: 5

Ferguson holds the career edge, of course, with 15 domestic titles (12 at United and three with Aberdeen) to Mourinho’s six (two each at Porto, Chelsea and Inter). Both have won the Champions League twice.